不同pH的溶出介质对HPMC骨架片释药的影响

目的　探讨溶出介质的pH对难溶性药物的HPMC骨架片释药的影响。方法　以甲氧苄胺嘧啶、卡马西平、磺胺甲恶唑和茶碱四种难溶型性药物为模型药物,测定四种pH缓冲溶液介质(pH1.0 ,pH4 .0 ,pH6 .0 ,pH7.5 )下的药物的溶解度和释放度。结果　难溶性药物的HPMC骨架片释药随着其溶解度的增加而加快。结论　难溶性药物HPMC骨架片释药的差异主要与药物在不同pH的溶出介质中的溶解度有关。     

不同pH的溶出介质对HPMC骨架片释药的影响

目的探讨溶出介质的pH对难溶性药物的HPMC骨架片释药的影响.方法以甲氧苄胺嘧啶、卡马西平、磺胺甲恶唑和茶碱四种难溶型性药物为模型药物,测定四种pH缓冲溶液介质(pH1.0,pH4.0,pH6.0,pH7.5)下的药物的溶解度和释放度.结果难溶性药物的HPMC骨架片释药随着其溶解度的增加而加快.结论难溶性药物HPMC骨架片释药的差异主要与药物在不同pH的溶出介质中的溶解度有关.     

稀释剂对HPMC骨架片释药的影响

目的　探讨稀释剂对难溶性药物的HPMC骨架片释药的影响。方法　以甲氧苄胺嘧啶、卡马西平、磺胺甲 口 恶 唑和茶碱四种难溶型性药物为模型药物 ,测定三种相同剂量的稀释剂 (糊精、乳糖和磷酸氢钙 )时药物的释放度。结果　甲氧苄胺嘧啶、卡马西平、磺胺甲 口恶 唑的释药速率为糊精 >乳糖 >磷酸氢钙 ;而茶碱的释药速率为糊精≈乳糖 >磷酸氢钙。结论　稀释剂对难溶性药物HPMC骨架片释药的影响同药物HPMC骨架片的释药机制有关     

黄原胶亲水性骨架片体外释药的影响因素

以茶碱为模型药物,制备了黄原胶亲水性骨架片,研究了体外释药的影响因素．结果表明,茶碱黄原胶亲水性骨架片的释药速率与骨架片中黄原胶的用量和溶出条件（ 转速、介质离子强度、ｐＨ 值） 有关,但与制备工艺条件无关．溶出介质中离子对其释药机制有影响．黄原胶能有效控制骨架片中药物释放,是一种优良的亲水性骨架材料．     

氢氯噻嗪HPMC骨架片释药机制影响因素研究

目的 研究影响HPMC骨架释药机制的因素。方法 以氢氯噻嗪为模型药物,HPMC为骨架材料,制备缓释片,测定释放度并描述其释放机制。考察各处方因素和释放条件对释放机制的影响。结果 HPMC用量越大、难溶性填充剂,释放机制越趋向于零级释放。较低的HPMC用量、水溶性填充剂,释放机制趋向于Higuchi和Peppas方程,释药行为以溶蚀和扩散相结合。结论 HPMC型号、片剂的硬度、制备方法、溶出度测定方法、转速对释放机制影响不大。HPMC用量、填充剂的性质、溶出介质的离子强度影响释放机制。     

氢氯噻嗪HPMC骨架片释药机制影响因素研究

目的研究影响HPMC骨架释药机制的因素。方法以氢氯噻嗪为模型药物,HPMC为骨架材料,制备缓释片,测定释放度并描述其释放机制。考察各处方因素和释放条件对释放机制的影响。结果 HPMC用量越大、难溶性填充剂,释放机制越趋向于零级释放。较低的HPMC用量、水溶性填充剂,释放机制趋向于Higuchi和Peppas方程,释药行为以溶蚀和扩散相结合。结论 HPMC型号、片剂的硬度、制备方法、溶出度测定方法、转速对释放机制影响不大。HPMC用量、填充剂的性质、溶出介质的离子强度影响释放机制。     

载盐酸普萘洛尔的SWELSTARTM MX-1骨架片及羟丙甲纤维素骨架片体外释药的比较

以水溶性药物盐酸普萘洛尔为模型药,分别制备了SWELSTARTM MX-1(下称MX-1)骨架片和羟丙甲纤维素(HPMC)骨架片.考察了两种空白骨架片在4种介质[0.1 mol/L盐酸、pH 6.8和7.2磷酸盐缓冲液(PBS)、水]中的吸水膨胀和溶蚀情况.结果表明,介质的pH和离子强度对MX-1骨架片的吸水膨胀和溶蚀无显著影响,而对HPMC骨架片的影响较大.采用零级、一级、Higuchi和Ritger-Peppas模型拟合两种骨架片在4种介质中的释药行为.结果表明,HPMC骨架片在pH 7.2 PBS中的释放比其他3种介质中快,而MX-1骨架片在4种介质中的释放行为没有明显变化.两种骨架片在4种介质中的释药机制均为药物扩散和骨架溶蚀协同作用,累积释放率数据均符合Ritger-Peppas模型.本研究表明,MX-1比HPMC有更好的抗高离子强度能力.     

介质和释放度测定方法对不同类型骨架片释药的影响

分别以不同的释放介质或释放度测定方法测定了模型药物盐酸氢吗啡酮在羟丙甲纤维素(HPMC)骨架片、十八醇骨架片、乙基纤维素骨架片和HPMC-十八醇混合骨架片中的释放行为.结果表明,释放介质的离子强度对含HPMC的骨架片的释药有影响;采用不同的测定方法对含十八醇或HPMC的骨架片有显著差异.     

改良HPMC-Synchron的应用

HPMC(羟丙基甲基纤维素)作为一种优良的粘合剂、助溶出剂和薄膜包衣材料,正逐渐在我国制剂工业中被推广应用。HPMC在水中能缓设溶解,且不受介质pH的影响,利用这种特性HPMC还可以用作不溶性骨架绥释片的致孔剂、亲水性凝胶缓释片的骨架材料和缓释制剂的包衣材料等,此外还可与难溶性药物制成固体分散剂,提高药物的溶出度、生物利用度以及药品质量的稳定性。美国Forest厂研究利用湿热处理HPMC,使之水解和氧化而获得一种改良的HPMC。处理前的HPMC(Methocel E50)羰基含量低于0.9％(W/W),羧基含     

特拉唑嗪单芯渗透泵片研制及其控制释放的因素

目的：研制难溶性药物特拉唑嗪的单芯渗透泵。方法：片芯中加入亲水性高分子，用乙基纤维素溶液包衣制备单尊渗透泵，并研究片芯处方、释药孔径等因素对释药行为的影响。结果：在0．80-1．15mm范围内，孔径对制备的渗透泵片释药行为没有影响，且自制渗透泵片在0～24h释放速度平稳，与胃肠道环境pH值和溶出仪转速无关。结论：制备的单芯渗透泵     

Swelling and drug release behaviour of xanthan gum matrix tablets

The swelling and drug release behaviour of xanthan gum matrix tablets were studied using three drugs having different properties, i.e., caffeine as a soluble neutral drug, indomethacin as an insoluble acidic drug, and the sodium salt of indomethacin as a soluble acidic drug. Swelling was ascertained by measuring the axial and the radial expansion of matrix tablets following exposure to media of physiological ionic strength. The mean drug dissolution time and swelling rate were calculated from dissolution and swelling experiments, respectively, and were used as responses for comparison under different experimental conditions. The dependence of drug release on the swelling of the polymer matrix and on the type of the drugs added was established. The former is mainly influenced by the ionic strength and buffer concentrations. The latter is affected by the solubility of the drug. The mechanism of matrix swelling follows Case I diffusion, whereas drug release from this polymer matrix conforms to Case II diffusion.     

羟丙基甲基纤维素骨架片的水渗透、骨架膨胀和药物释放性质

当HPMC骨架与水接触时,可以观察到水渗透进入HPMC骨架的过程。HPMC取代度类型对水渗透作用的影响集中表现在最初较短的一段时间内,这段时间是指HPMC形成水凝胶的时间。水凝胶形成后,水渗透进入凝胶的速率是恒定的。HPMC对水渗透作用的影响取决于其分子量。当HPMC骨架中加入药物后,水渗透进入骨架的能力会变弱。当水渗透进入HPMC骨架时,骨架可发生明显的膨胀,其轴向膨胀比径向膨胀大得多,骨架的膨胀主要由HPMC产生,骨架中HPMC含量越高,其膨胀程度越大。水渗透、骨架膨胀与药物释放之间存在线性相关性。     

Aqueous ethyl cellulose dispersions containing plasticizers of different water solubility and hydroxypropyl methylcellulose as coating material for diffusion pellets. I. Drug release rates from coated pellets

The present work investigates release mechanisms of theophylline pellets coated with an aqueous ethyl cellulose (EC) dispersion containing plasticizers and hydroxypropyl methylcellulose (HPMC) as a water soluble pore former. Three different drug release mechanisms from coated pellets can be determined as a function of the water solubility of the plasticizers and the ionic strength of the release medium. Coated pellets with the addition of more hydrophilic plasticizers such as triethyl citrate (TEC) or diethyl phthalate (DEP) show an approximate zero-order-release rate. In contrast, two-phase release profiles can be observed from pellets coated with dispersions containing hardly soluble plasticizers such as dibutyl phthalate (DBP) or dibutyl sebacate (DBS). Only in a release medium of high ionic strength the water soluble pore former will remain in the coating. Thus the drug diffuses through a hydrated swollen membrane containing EC, HPMC and insoluble plasticizer. The release mechanisms depend on the glass transition temperature of the ethyl cellulose and therefore on the migration of the plasticizers and the pore former. This was shown by investigation of the migration of the additives and the influence of the temperature of the release medium on the release. Additionally, the study investigates the effect of curing and storage conditions of coated pellets on the drug release rate.     

Photostability of extended-release matrix formulations.

The photostability of drugs has been widely studied while less attention is devoted to the possible modifications that UV light may induce on the excipients of a dosage form, in particular, on the functional polymers used to modulate drug delivery. In this work we have evaluated the effect of UV light on the release characteristics of extended-release matrix tablets containing hydroxypropylmethylcellulose (HPMC) or polyethylene oxide (PEO) as retarding polymers. Two different model drugs have been used: nifedipine (insoluble and photolabile drug) and diltiazem (soluble and photostable drug). Photodecomposition of nifedipine was evaluated and the formation of the photoproducts was followed during the dissolution process. Regarding the dissolution stability, the matrix tablets containing HPMC exposed to UV light have not shown significant differences in drug release profiles compared to the same non-irradiated formulation, while the matrix tablets containing PEO and exposed to the same conditions of UV light have shown a remarkable increase of drug release rate within the first minutes of the dissolution test (burst effect) which is particularly critical because it can cause the loss of the desired therapeutic control.     

羟丙基甲基纤维素的性质对药物亲水性骨架片溶出度的影响

考察了羟丙基甲基纤维素（ＨＰＭＣ）的羟丙基含量、ＨＰＭＣ颗粒大小和ＨＰＭＣ的粘度对模型药物卡托普利、扑尔敏和蚓哚美辛（消炎痛）骨架片药物溶出的作用。结果表明药物溶解度不同对骨架片中ＨＰＭＣ不同性质的影响也不同。ＨＰＭＣ羟丙基含量增高，溶出速率加快；而卡托普利和扑尔敏则相反。ＨＰＭＣ颗粒大小对卡托普利和扑尔敏骨架片溶出影响较小，但对蚓跺美辛骨架片有一定影响，表现为ＨＰＭＣ颗粒越小，溶出速率越慢。由ＨＰＭＣＫ１００构制的骨架片对３种药物均达不到阻滞释放的作用。ＨＰＭＣＫ４Ｍ，Ｋ１５Ｍ和Ｋ１００Ｍ的粘度差异对卡托普利和扑尔敏的溶出影响不大，但随着粘度增加吲跺美辛的溶出速率减慢。     

愈创甘油醚缓释片的研究

目的研究1天给药2次的愈创甘油醚骨架型缓释片。方法以HPMC为骨架材料,采用正交试验设计,考察HPMC的不同型号和不同用量对释放度的影响,筛选出最佳处方。结果体外释放度实验表明,缓释片比普通片释药时间延长,其体外释放行为符合Higuchi(r=09915)方程。结论该缓释片处方工艺简单,适合工业化生产;缓释效果明显。